fossil

Fossilized Coral

Cnidaria fossil / Calcite-replaced coral

Hardness: 3 to 4 on Mohs scale (due to replacement by calcite or quartz), Color: Tan, brown, or yellowish-grey, Luster: Dull to vitreous, Structure: Retains the porous, branching, or honeycomb colonial structure of the original coral skeleton.

Identified August 1, 2026More fossil →

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Physical properties

Formation & geological history

Formed in warm, shallow marine environments over millions of years (often Paleozoic to Cenozoic eras), where the original coral aragonite skeletons are gradually replaced by minerals like silica or calcite through permineralization or replacement.

Uses & applications

Used primarily in lapidary work for making cabochons, decorative carvings, jewelry, and as educational or display specimens for fossil and rock collectors.

Geological facts

Fossil coral is often the state stone of Florida and can sometimes be agatized, meaning the original organic structure has been completely replaced by microcrystalline quartz.

Field identification & locations

Easily identified in the field by its distinct honeycomb or star-like patterned pores. Commonly found in limestone quarries, ancient seabed deposits, and riverbeds where sedimentary rock is exposed.

Other fossil specimens

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Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil

Sedimentary Outcrop (Sandstone/Shale)

Sedimentary bedrock formation (variable composition)

sedimentary

Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

sedimentary

Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

fossil

Fossiliferous Limestone

Limestone with embedded fossil cross-section

sedimentary

Fossiliferous Limestone with Crinoid stems

Limestone (CaCO3) containing Crinoidea fossils

sedimentary